On the first morning of the Trent Bridge Test match, Australia batted first and at the first drinks break were 38 for 7, their top seven all back in the pavilion. England started batting 50 minutes later and an hour into their innings were 30 for 0. The Ashes were, barring a freak turnaround, already on their way back to England.

What happened? Why did Australia collapse so dramatically? Great bowling? Poor batting? A green-topped, bowlers’ dream that simply handed the match to the captain lucky enough to win the toss?

Why was the first hour of England’s innings so different to that of Australia’s an hour and a half earlier?

Did the conditions get easier?

A little. The ball kept swinging; the average deviation in the air when the Australians bowled was 2.1 degrees, slightly more than the 1.9 degrees when England bowled. Both teams swung roughly 60% of the balls they bowled by more than 1.5 degrees, the amount of swing that starts to have a significant impact on a batsman’s performance.

There was more seam movement when Australia batted. 31% of the balls in the first hour deviated by more than one degree off the pitch, whereas the figure when England batted was 18%. The average seam movement faced was 0.7 degrees for Australia and 0.5 degrees for England.

However, this was part of a pattern in the series. England’s seamers got more lateral movement off the wicket and were more accurate throughout; the Australian pacemen consistently bowled a little quicker on average and got more movement in the air.

Conditions had got a little easier by the time England batted, but not drastically so.

Did England out-bowl Australia?

England, and Stuart Broad in particular, bowled very well. A traditional good length in Test cricket is usually defined as balls pitching six to eight metres from the stumps. These are the balls that have the lowest average (runs per wicket), regardless of pitch, conditions and opposition. When the ball is moving around in the air and off the wicket, the metre or so fuller than that (5-6m from the stumps) becomes equally, if not even more, dangerous. England landed just over 60% of their deliveries in these areas, and these balls accounted for all but one of the wickets in that innings. Australia though, bowled even more balls on these lengths, 67% in their first 11 overs.

The England bowlers also bowled unusually straight. Their average line was middle and off, very straight for Test cricket; 49% of the balls they bowled were within the line of leg stump and six inches outside off stump. It was the balls on these lines that did the bulk of the damage to the Australian top order.

Australia bowled significantly wider. Their average line was six inches outside off stump – they put 52% of their deliveries wide of this mark, compared to 35% of England’s. This allowed England’s batsmen more easy leaves than the Australians got, nearly half as many again.

So, as was the case all summer, better areas and more movement off the pitch from England, albeit at a slightly slower pace. When the pitch offered assistance, England were the more dangerous attack. When it didn’t, Australia’s pace and swing posed the greater threat. Trent Bridge was no minefield, but nor was it the pitch where you wanted your great strength to be taking the pitch out of the equation.

Did Australia go too hard at the ball? Play too many shots? Not leave well enough?

Using the BatViz system we can compare how Australia played the deliveries they faced with how an average Test side would have played them.

Given the balls they faced, we would have expected 25 attacking shots in the first hour. Australia played 22. BatViz projected 14.5 balls to be left; they played no shot on 19 occasions.

For comparison, we would have expected England to play 24.5 attacking shots and they played 21. They got more balls to leave, as Australia bowled wider than England. 17.5 leaves were forecast – they actually left the ball 25 times.

First hour BatViz shot analysis

Australia

England

Attacking shots

Expected

25

24.5

Actual

22

21

Leaves

Expected

14.5

17.5

Actual

19

25

There therefore seems to have been little difference in the overall intent of the two sides and it is worth noting that only three of the seven Australian wickets fell to attacking shots. That might be three too many given the situation and conditions, but it is easy to criticise attacking shots when they don’t come off and applaud them when they do: England showed a very similar level of attacking intent and left the ball marginally better.

Was it therefore poor shot selection and execution?

Given the balls received, BatViz projected 11.9 false shots – edges and misses – from the Australians. There were 19. For comparison, we would have expected eight false shots from England and there were just six (five misses and one edge). On average in 11 overs of Test cricket there would be 4.5 false shots.

England had to play fewer balls and the balls they played at moved a little less. They also played them better than par, whereas the Australians underperformed against the balls they faced.

First hour BatViz false shot analysis

Australia

England

False shots - predicted

11.9

8

False shots - actual

19

6

Missed

10

5

Edged

9

1

Wickets from edge

6

0

Even so, 19 false shots to six can’t be the difference between seven down and no wickets very often.

So were Australia just unlucky?

They certainly were to an extent. Of their 19 false shots, nine were edges (47%). Generally only about 37% of false shots are edges, so they were unlucky to nick almost as many as they missed. England played and missed five times for their solitary edge.

About 15% of edges result in a wicket. Australia’s nine edges produced six wickets, so the picture of a perfect storm is forming. The pitch had good carry, so there was little chance of edges with the new ball falling short of the slip cordon. The England bowlers’ areas were good, so the edges produced were more likely to find catchers than fly to safety. Two wickets in the first over meant that for the remainder of the innings Alastair Cook employed five or six catchers, so any edge was likely to find a catcher rather than a gap.

And what about the catching?

The first hour brought five slip catches, the innings as a whole comprised eight. Every single one of the chances offered were held, including Ben Stokes’ stunning one-handed grab.

On average in Test cricket roughly 70% of slip catches are caught. PlayViz goes deeper by rating chances according to where they come and the reaction time the fielder has. In doing so we can estimate that the five chances presented in the first hour would normally have resulted in two or three wickets (2.65 to be exact): the English cordon hugely over-performed.

A bit of everything?

The Australians were hit by a perfect storm of several factors, each multiplying the effect of the others that together created a manic 11 overs that devastated their Ashes dreams.

The ball swung and seamed enough to trouble the batsmen. The bowlers – Broad in particular – used the conditions very skilfully, and allowed the batsmen little respite. The Aussies didn’t cope with the moving ball particularly well and didn’t have a lot of luck when it came to playing and missing. A pitch with good pace and bounce ensured the edges carried and early wickets meant a packed slip cordon. The chances went to hand and the fielders caught exceptionally well. 38 for 7. Ashes gone.